Electric lamp manufacture



Oct. 12, 1965 v LEVAND, JR 3,211,511

ELECTRIC LAMP MANUFACTURE Filed Jan. 30, 1963 & Fi .5. W i 4. 2 w 5 by Fig 3. if; w

g 4 4 4 L. i 3 -7 rw #40 2 3 3 6 H 8 W2 2m l2 z 6& 5 #3 l Riga lnvan t-ov:

gag Vic tor A. Levand, Jr.

by M /1'/ His A t to e5 United States Patent 3,211,511 ELECTRIC LAMP MANUFACTURE Victor A. Levand, Jr., Cleveland, Ohio, assignor to General Electric Company, a corporation of New York Filed Jan. 30, 1963, Ser. No. 254,934 3 Claims. (Cl. 316-19) This invention relates generally to the manufacture of electric incandescent lamps, and more particularly to the manufacture of lamps of .the double-ended type comprising an elongated tubular envelope having therein a longitudinally extending filament connected at its ends to lead-in conductors extending through sealed end portions of the envelope.

In the manufacture of certain species of such lamps it has been the practice to provide the envelope with an exhaust tube extending laterally therefrom, usually at its midpoint. The envelope is exhausted and usually filled with a desired gas through said exhaust tube which is subsequently tipped off close to the envelope. The resulting tip has certain disadvantages such as distortion of the light, susceptibility to breakage and interference with closely fitting reflectors.

It is accordingly a principal object of the present invention to provide a method of manufacturing a tipless lamp of the tubular double-ended type.

For a full understanding of the invention reference is directed to the following detailed description and to the drawing wherein:

FIG. 1 is an elevation of an assembly of the lamp envelope and exhaust tube;

FIG. 2 is a fragmentary view showing the preliminary seal of the exhaust tube into the proximate end of the envelope;

FIGS. 3 and 4 are sections through the preliminary seal taken along the lines 33 and 4-4 of FIG. 2;

FIG. 5 is an elevation showing the assembly of the filament and envelope;

FIG. 6 is an elevation, at right angles to FIG. 5, showing the completed seal at the lower end of the lamp;

FIG. 7 is an elevation illustrating completion of the lamp by exhausting and gas filling the envelope, sealing the upper end and removing the exhaust tube; and

FIG. 8 is a section through the upper seal along the line 8-8 in FIG. 7.

In accordance with one aspect of the invention, the method of manufacture involves the steps of preliminarily sealing an end of an exhaust tube into one end of the tubular envelope while preserving the opening through the interior of the exhaust tube into the envelope, threading into the envelope an assembly of the coiled filament and attached lead-in conductors with one of the said conductors extending into the exhaust tube and held therein in any suitable manner, and with the other lead-in conductor extending outwardly through the other end of the envelope, fusing and sealing the said other end of the envelope about a portion of the said other lead-in conductor, exhausting and gas filling the envelope through the exhaust tube, and then sealing closed the end of the envelope containing the exhaust tube and associated leadin conductor, and finally removing the portion of exhaust tubing extending from the last mentioned end of the envelope, as by simply snapping it off.

The following detailed description, in certain specific aspects, is directed particularly to a lamp of the so-called iodine cycle type disclosed and claimed in U.S. Patent 2,883,571- Fridrich and Wiley, which is assigned to the same assignee as the present invention.

Referring to FIG. 1 of the drawing, there is shown an assembly of tubular lamp envelope 1 and exhaust tube 2 of suitable vitreous material such as a hard glass of M 3,211,511 Patented Oct. 12, 1965 high melting point and low expansion, or of quartz. With the lower end of the envelope 1 concentrically surrounding the upper end of the exhaust tube 2, the said en velope end is heated by suitable gas burners and compressed and sealed about the exhaust tube, preferably by pinch sealing with the aid of suitable pinch jaws of known type which are relieved at the center to avoid closing the opening through the exhaust tube, as illustrated by the showing of the resulting preliminary seal at 3 in FIGS. 2, 3 and 4.

There is then threaded into the envelope a filament assembly (FIG. 5) comprising a helically coiled tungsten wire filament 4 having lead-in conductors 5 and 6 attached to respective ends thereof, and suitable support members such as tungsten wire spirals 7 which are attached to the filament at spaced intervals therealong and which serve to support the filament from the envelope walls. The upper lead-in conductor 5 is provided with an extension and is held against longitudinal movement in any suitable manner, in this case by being bent over the outer end of the exhaust tube 2 as 'shown at 8. With an envelope 1 of quartz, the lead-in wires 5 and 6 are preferably made of molybdenum with extremely thin flattened end portions 9 and 10 for forming a hermetic seal with the quartz. The crimp or bend 8 in the extension of lead wire 5 is so located that the filament 4 is properly stretched when the other (lower) lead wire 6 is held in proper sealing relation to the lower end of the envelope 1, the said lead Wire 6 being shown in FIG. 5 as located in an axial bore of a sealing head 11 and clamped therein by a spring biased finger or plunger 12.

The lower end of the envelope 1 (FIG. 5) is then softened by heating and pinched about the lead-in conductor 6 by suitable pinch jaws to form a pinch seal as illustrated at 13 in FIG. 6 with the seal portion 10 of the lead wire hermetically sealed therein.

The lamp is next exhausted and gas filled through the exhaust tube 2. For this purpose the exhaust tube 2 may be inserted into the head or port of an exhaust machine. The air is exhausted from the envelope 1 which is also filled with a suitable gas, for example argon and a small quantity of iodine vapor. During the exhausting and flushing of the envelope the filament 4 may be energized by providing for electrical connection within the exhaust head to the bent end 8 of the lead Wire 5.

In order to facilitate sealing the upper end of the envelope, and also to provide a gas pressure above atmospheric at room temperatures, the envelope is cooled, as by immersing the lower end thereof in liquid nitrogen contained in a receptacle 14 to reduce the gas pressure below atmospheric as Well as to condense the iodine vapor. The upper end of the envelope may then be sealed by simply heating the central portion of the seal area 3 to cause it to collapse and close upon the lead wire 5 and the adjacent end portion of the filament 4, as illustrated in FIG. 8. If desired, the formation of the seal may be assisted by compressing the heated area with pinch jaws. The lamp is then completed by removing the extending portion of the exhaust tube 2 in any suitable manner, as by simply snapping it off, so that the envelope is devoid of any projecting exhaust tip. The envelope 1 may thus be filled with gas to any suitable pressure, for example 1400 mm. Hg of argon at ordinary room temperature (70 F.).

It will be evident to those skilled in the art that various changes, modifications and omissions may be made Within the spirit and scope of the invention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In the manufacture of a tipless double-ended incandescent lamp, the steps which comprise arranging an end portion of an exhaust tube of vitreous material directly within a first end portion of an elongated tubular envelope of vitreous material, heating and softening the said first end portion of said envelope and preliminarily collapsing it upon and fusing around the said end portion of the exhaust tube while maintaining the opening through said exhaust tube to the interior of the envelope, threading into the envelope at filament assembly comprising a coiled filament having first and second lead-in conductors attached to respective ends thereof and maintaining the resulting assembly with the said first conductor extending into and through said exhaust tube and held therein against longitudinal movement and the said second conductor extending along and outwardly through the second end of said envelope with the filament stretched taut between said conductors, sealing the said second end of the envelope with a portion of the second conductor sealed therein, evacuating and filling the envelope with a desired atmosphere through said exhaust tube while heating said filament by passage of electric current therethrough during at least part of the operations of evacuating and filling the envelope, heating and sealing closed the preliminarily collapsed first end portion of said envelope with a portion of the first conductor sealed therein,

and removing the portion of said exhaust tube extending from the sealed first end of the envelope.

2. The manufacture of an incandescent lamp as set forth in claim 1 wherein the said first conductor is held in place in said exhaust tube by an extension thereof projecting from and bent around the end of said exhaust tube.

3. The manufacture of an incandescent lamp as set forth in claim 1 wherein, in the course of evacuating and filling the envelope with a desired atmosphere, it is filled with gas at a pressure above atmospheric at ordinary room temperature, the envelope is chilled to reduce and maintain the said gas pressure below atmospheric during the step of heating and sealing the first end of the en velope so that said first end of the envelope is collapsed and sealed closed around a portion of said first conductor.

References Cited by the Examiner UNITED STATES PATENTS 263,304 8/92 Betts 316l9 2,683,837 7/54 Hager 316-19 2,870,586 1/59 Pearson et al.

FRANK E. BAILEY, Primary Examiwer. 

1. IN THE MANUFACTURE OF A TIPLESS DOUBLE-ENDED INCANDESCENT LAMP, THE STEPS WHICH COMPRISE ARRANGING IN END PORTION OF AN EXHAUST TUBE OF VITREOUS MATERIAL DIRECTLY WITHIN A FIRST END PORTION OF AN ELONGATED TUBULAR ENVELOPE OF VITREOUS MATERIAL, HEATING AND SOFTENING THE SAID FIRST END PORTION OF SAID ENVELOPE AND PRELIMINARILY COLLAPSING IT UPON AND FUSING AROUND THE SAID END PORTION OF THE EXHAUST TUBE WHILE MAINTAINING THE OPENING THROUGH SAID EXHAUST TUBE TO THE INTERIOR OF THE ENVELOPE, THREADING INTO THE ENVELOPE A FILAMENT ASSEMBLY COMPRISING A COILED FILAMENT HAVING FIRST AND SECOND LEAD-IN CONDUCTORS ATTACHED TO RESPECTIVE ENDS THEREOF AND MAINTAINING THE RESULTING ASSEMBLY WITH THE SAID FIRST CONDUCTOR EXTENDING INTO AND THROUGH SAID EXHAUST TUBE AND HELD THEREIN AGAINST LONGITUDINAL MOVEMENT AND THE SAID SECOND CONDUCTOR EXTENDING ALONG AND OUTWARDLY THROUGH THE SECOND END OF SAID ENVELOPE WITH THE FILAMENT STRETCHED TAUT BETWEEN SAID CONDUCTORS, SEALING THE SAID SECOND END OF THE ENVELOPE WITH A PORTION OF THE SECOND CONDUCTOR SEALED THEREIN, EVACUATING THROUGH AID EXHAUST TUBE WHILE A DESIRED ATMOSPHERE THROUGH SAID EXHAUST TUBE WHILE HEATING SAID FILAMENT BY PASSAGE OF ELECTRIC CURRENT THERETHROUGH DURING AT LEAST PART OF THE OPERATIONS OF EVACUATING AND FILLING THE ENVELOPE, HEATING AND SEALING CLOSED THE PRELIMINARILY COLLAPSED FIRST END PORTION OF SAID ENVELOPE WITH A PORTION OF THE FIRST CONDUCTOR SEALED THEREIN, AND REMOVING THE PORTION OF SAID EXHAUST TUBE EXTENDING FROM THE SEALED FIRST END OF SAID ENVELOPE. 